diff options
Diffstat (limited to 'src/libshared/machine-image.c')
| -rw-r--r-- | src/libshared/machine-image.c | 818 |
1 files changed, 818 insertions, 0 deletions
diff --git a/src/libshared/machine-image.c b/src/libshared/machine-image.c new file mode 100644 index 0000000000..529d89ee2a --- /dev/null +++ b/src/libshared/machine-image.c @@ -0,0 +1,818 @@ +/*** + This file is part of systemd. + + Copyright 2013 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <dirent.h> +#include <errno.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/file.h> +#include <sys/stat.h> +#include <unistd.h> +#include <linux/fs.h> +#include "alloc-util.h" +#include "btrfs-util.h" +#include "chattr-util.h" +#include "copy.h" +#include "dirent-util.h" +#include "fd-util.h" +#include "fs-util.h" +#include "hashmap.h" +#include "lockfile-util.h" +#include "log.h" +#include "macro.h" +#include "machine-image.h" +#include "mkdir.h" +#include "path-util.h" +#include "rm-rf.h" +#include "string-table.h" +#include "string-util.h" +#include "strv.h" +#include "time-util.h" +#include "utf8.h" +#include "util.h" +#include "xattr-util.h" + +static const char image_search_path[] = + "/var/lib/machines\0" + "/var/lib/container\0" /* legacy */ + "/usr/local/lib/machines\0" + "/usr/lib/machines\0"; + +Image *image_unref(Image *i) { + if (!i) + return NULL; + + free(i->name); + free(i->path); + free(i); + return NULL; +} + +static char **image_settings_path(Image *image) { + _cleanup_strv_free_ char **l = NULL; + char **ret; + const char *fn, *s; + unsigned i = 0; + + assert(image); + + l = new0(char*, 4); + if (!l) + return NULL; + + fn = strjoina(image->name, ".nspawn"); + + FOREACH_STRING(s, "/etc/systemd/nspawn/", "/run/systemd/nspawn/") { + l[i] = strappend(s, fn); + if (!l[i]) + return NULL; + + i++; + } + + l[i] = file_in_same_dir(image->path, fn); + if (!l[i]) + return NULL; + + ret = l; + l = NULL; + + return ret; +} + +static int image_new( + ImageType t, + const char *pretty, + const char *path, + const char *filename, + bool read_only, + usec_t crtime, + usec_t mtime, + Image **ret) { + + _cleanup_(image_unrefp) Image *i = NULL; + + assert(t >= 0); + assert(t < _IMAGE_TYPE_MAX); + assert(pretty); + assert(filename); + assert(ret); + + i = new0(Image, 1); + if (!i) + return -ENOMEM; + + i->type = t; + i->read_only = read_only; + i->crtime = crtime; + i->mtime = mtime; + i->usage = i->usage_exclusive = (uint64_t) -1; + i->limit = i->limit_exclusive = (uint64_t) -1; + + i->name = strdup(pretty); + if (!i->name) + return -ENOMEM; + + if (path) + i->path = strjoin(path, "/", filename, NULL); + else + i->path = strdup(filename); + + if (!i->path) + return -ENOMEM; + + path_kill_slashes(i->path); + + *ret = i; + i = NULL; + + return 0; +} + +static int image_make( + const char *pretty, + int dfd, + const char *path, + const char *filename, + Image **ret) { + + struct stat st; + bool read_only; + int r; + + assert(filename); + + /* We explicitly *do* follow symlinks here, since we want to + * allow symlinking trees into /var/lib/machines/, and treat + * them normally. */ + + if (fstatat(dfd, filename, &st, 0) < 0) + return -errno; + + read_only = + (path && path_startswith(path, "/usr")) || + (faccessat(dfd, filename, W_OK, AT_EACCESS) < 0 && errno == EROFS); + + if (S_ISDIR(st.st_mode)) { + _cleanup_close_ int fd = -1; + unsigned file_attr = 0; + + if (!ret) + return 1; + + if (!pretty) + pretty = filename; + + fd = openat(dfd, filename, O_CLOEXEC|O_NOCTTY|O_DIRECTORY); + if (fd < 0) + return -errno; + + /* btrfs subvolumes have inode 256 */ + if (st.st_ino == 256) { + + r = btrfs_is_filesystem(fd); + if (r < 0) + return r; + if (r) { + BtrfsSubvolInfo info; + + /* It's a btrfs subvolume */ + + r = btrfs_subvol_get_info_fd(fd, 0, &info); + if (r < 0) + return r; + + r = image_new(IMAGE_SUBVOLUME, + pretty, + path, + filename, + info.read_only || read_only, + info.otime, + 0, + ret); + if (r < 0) + return r; + + if (btrfs_quota_scan_ongoing(fd) == 0) { + BtrfsQuotaInfo quota; + + r = btrfs_subvol_get_subtree_quota_fd(fd, 0, "a); + if (r >= 0) { + (*ret)->usage = quota.referenced; + (*ret)->usage_exclusive = quota.exclusive; + + (*ret)->limit = quota.referenced_max; + (*ret)->limit_exclusive = quota.exclusive_max; + } + } + + return 1; + } + } + + /* If the IMMUTABLE bit is set, we consider the + * directory read-only. Since the ioctl is not + * supported everywhere we ignore failures. */ + (void) read_attr_fd(fd, &file_attr); + + /* It's just a normal directory. */ + r = image_new(IMAGE_DIRECTORY, + pretty, + path, + filename, + read_only || (file_attr & FS_IMMUTABLE_FL), + 0, + 0, + ret); + if (r < 0) + return r; + + return 1; + + } else if (S_ISREG(st.st_mode) && endswith(filename, ".raw")) { + usec_t crtime = 0; + + /* It's a RAW disk image */ + + if (!ret) + return 1; + + fd_getcrtime_at(dfd, filename, &crtime, 0); + + if (!pretty) + pretty = strndupa(filename, strlen(filename) - 4); + + r = image_new(IMAGE_RAW, + pretty, + path, + filename, + !(st.st_mode & 0222) || read_only, + crtime, + timespec_load(&st.st_mtim), + ret); + if (r < 0) + return r; + + (*ret)->usage = (*ret)->usage_exclusive = st.st_blocks * 512; + (*ret)->limit = (*ret)->limit_exclusive = st.st_size; + + return 1; + } + + return 0; +} + +int image_find(const char *name, Image **ret) { + const char *path; + int r; + + assert(name); + + /* There are no images with invalid names */ + if (!image_name_is_valid(name)) + return 0; + + NULSTR_FOREACH(path, image_search_path) { + _cleanup_closedir_ DIR *d = NULL; + + d = opendir(path); + if (!d) { + if (errno == ENOENT) + continue; + + return -errno; + } + + r = image_make(NULL, dirfd(d), path, name, ret); + if (r == 0 || r == -ENOENT) { + _cleanup_free_ char *raw = NULL; + + raw = strappend(name, ".raw"); + if (!raw) + return -ENOMEM; + + r = image_make(NULL, dirfd(d), path, raw, ret); + if (r == 0 || r == -ENOENT) + continue; + } + if (r < 0) + return r; + + return 1; + } + + if (streq(name, ".host")) + return image_make(".host", AT_FDCWD, NULL, "/", ret); + + return 0; +}; + +int image_discover(Hashmap *h) { + const char *path; + int r; + + assert(h); + + NULSTR_FOREACH(path, image_search_path) { + _cleanup_closedir_ DIR *d = NULL; + struct dirent *de; + + d = opendir(path); + if (!d) { + if (errno == ENOENT) + continue; + + return -errno; + } + + FOREACH_DIRENT_ALL(de, d, return -errno) { + _cleanup_(image_unrefp) Image *image = NULL; + + if (!image_name_is_valid(de->d_name)) + continue; + + if (hashmap_contains(h, de->d_name)) + continue; + + r = image_make(NULL, dirfd(d), path, de->d_name, &image); + if (r == 0 || r == -ENOENT) + continue; + if (r < 0) + return r; + + r = hashmap_put(h, image->name, image); + if (r < 0) + return r; + + image = NULL; + } + } + + if (!hashmap_contains(h, ".host")) { + _cleanup_(image_unrefp) Image *image = NULL; + + r = image_make(".host", AT_FDCWD, NULL, "/", &image); + if (r < 0) + return r; + + r = hashmap_put(h, image->name, image); + if (r < 0) + return r; + + image = NULL; + + } + + return 0; +} + +void image_hashmap_free(Hashmap *map) { + Image *i; + + while ((i = hashmap_steal_first(map))) + image_unref(i); + + hashmap_free(map); +} + +int image_remove(Image *i) { + _cleanup_release_lock_file_ LockFile global_lock = LOCK_FILE_INIT, local_lock = LOCK_FILE_INIT; + _cleanup_strv_free_ char **settings = NULL; + char **j; + int r; + + assert(i); + + if (IMAGE_IS_VENDOR(i) || IMAGE_IS_HOST(i)) + return -EROFS; + + settings = image_settings_path(i); + if (!settings) + return -ENOMEM; + + /* Make sure we don't interfere with a running nspawn */ + r = image_path_lock(i->path, LOCK_EX|LOCK_NB, &global_lock, &local_lock); + if (r < 0) + return r; + + switch (i->type) { + + case IMAGE_SUBVOLUME: + r = btrfs_subvol_remove(i->path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA); + if (r < 0) + return r; + break; + + case IMAGE_DIRECTORY: + /* Allow deletion of read-only directories */ + (void) chattr_path(i->path, 0, FS_IMMUTABLE_FL); + r = rm_rf(i->path, REMOVE_ROOT|REMOVE_PHYSICAL|REMOVE_SUBVOLUME); + if (r < 0) + return r; + + break; + + case IMAGE_RAW: + if (unlink(i->path) < 0) + return -errno; + break; + + default: + return -EOPNOTSUPP; + } + + STRV_FOREACH(j, settings) { + if (unlink(*j) < 0 && errno != ENOENT) + log_debug_errno(errno, "Failed to unlink %s, ignoring: %m", *j); + } + + return 0; +} + +static int rename_settings_file(const char *path, const char *new_name) { + _cleanup_free_ char *rs = NULL; + const char *fn; + + fn = strjoina(new_name, ".nspawn"); + + rs = file_in_same_dir(path, fn); + if (!rs) + return -ENOMEM; + + return rename_noreplace(AT_FDCWD, path, AT_FDCWD, rs); +} + +int image_rename(Image *i, const char *new_name) { + _cleanup_release_lock_file_ LockFile global_lock = LOCK_FILE_INIT, local_lock = LOCK_FILE_INIT, name_lock = LOCK_FILE_INIT; + _cleanup_free_ char *new_path = NULL, *nn = NULL; + _cleanup_strv_free_ char **settings = NULL; + unsigned file_attr = 0; + char **j; + int r; + + assert(i); + + if (!image_name_is_valid(new_name)) + return -EINVAL; + + if (IMAGE_IS_VENDOR(i) || IMAGE_IS_HOST(i)) + return -EROFS; + + settings = image_settings_path(i); + if (!settings) + return -ENOMEM; + + /* Make sure we don't interfere with a running nspawn */ + r = image_path_lock(i->path, LOCK_EX|LOCK_NB, &global_lock, &local_lock); + if (r < 0) + return r; + + /* Make sure nobody takes the new name, between the time we + * checked it is currently unused in all search paths, and the + * time we take possession of it */ + r = image_name_lock(new_name, LOCK_EX|LOCK_NB, &name_lock); + if (r < 0) + return r; + + r = image_find(new_name, NULL); + if (r < 0) + return r; + if (r > 0) + return -EEXIST; + + switch (i->type) { + + case IMAGE_DIRECTORY: + /* Turn of the immutable bit while we rename the image, so that we can rename it */ + (void) read_attr_path(i->path, &file_attr); + + if (file_attr & FS_IMMUTABLE_FL) + (void) chattr_path(i->path, 0, FS_IMMUTABLE_FL); + + /* fall through */ + + case IMAGE_SUBVOLUME: + new_path = file_in_same_dir(i->path, new_name); + break; + + case IMAGE_RAW: { + const char *fn; + + fn = strjoina(new_name, ".raw"); + new_path = file_in_same_dir(i->path, fn); + break; + } + + default: + return -EOPNOTSUPP; + } + + if (!new_path) + return -ENOMEM; + + nn = strdup(new_name); + if (!nn) + return -ENOMEM; + + r = rename_noreplace(AT_FDCWD, i->path, AT_FDCWD, new_path); + if (r < 0) + return r; + + /* Restore the immutable bit, if it was set before */ + if (file_attr & FS_IMMUTABLE_FL) + (void) chattr_path(new_path, FS_IMMUTABLE_FL, FS_IMMUTABLE_FL); + + free(i->path); + i->path = new_path; + new_path = NULL; + + free(i->name); + i->name = nn; + nn = NULL; + + STRV_FOREACH(j, settings) { + r = rename_settings_file(*j, new_name); + if (r < 0 && r != -ENOENT) + log_debug_errno(r, "Failed to rename settings file %s, ignoring: %m", *j); + } + + return 0; +} + +static int clone_settings_file(const char *path, const char *new_name) { + _cleanup_free_ char *rs = NULL; + const char *fn; + + fn = strjoina(new_name, ".nspawn"); + + rs = file_in_same_dir(path, fn); + if (!rs) + return -ENOMEM; + + return copy_file_atomic(path, rs, 0664, false, 0); +} + +int image_clone(Image *i, const char *new_name, bool read_only) { + _cleanup_release_lock_file_ LockFile name_lock = LOCK_FILE_INIT; + _cleanup_strv_free_ char **settings = NULL; + const char *new_path; + char **j; + int r; + + assert(i); + + if (!image_name_is_valid(new_name)) + return -EINVAL; + + settings = image_settings_path(i); + if (!settings) + return -ENOMEM; + + /* Make sure nobody takes the new name, between the time we + * checked it is currently unused in all search paths, and the + * time we take possession of it */ + r = image_name_lock(new_name, LOCK_EX|LOCK_NB, &name_lock); + if (r < 0) + return r; + + r = image_find(new_name, NULL); + if (r < 0) + return r; + if (r > 0) + return -EEXIST; + + switch (i->type) { + + case IMAGE_SUBVOLUME: + case IMAGE_DIRECTORY: + /* If we can we'll always try to create a new btrfs subvolume here, even if the source is a plain + * directory.*/ + + new_path = strjoina("/var/lib/machines/", new_name); + + r = btrfs_subvol_snapshot(i->path, new_path, (read_only ? BTRFS_SNAPSHOT_READ_ONLY : 0) | BTRFS_SNAPSHOT_FALLBACK_COPY | BTRFS_SNAPSHOT_RECURSIVE | BTRFS_SNAPSHOT_QUOTA); + if (r == -EOPNOTSUPP) { + /* No btrfs snapshots supported, create a normal directory then. */ + + r = copy_directory(i->path, new_path, false); + if (r >= 0) + (void) chattr_path(new_path, read_only ? FS_IMMUTABLE_FL : 0, FS_IMMUTABLE_FL); + } else if (r >= 0) + /* Enable "subtree" quotas for the copy, if we didn't copy any quota from the source. */ + (void) btrfs_subvol_auto_qgroup(new_path, 0, true); + + break; + + case IMAGE_RAW: + new_path = strjoina("/var/lib/machines/", new_name, ".raw"); + + r = copy_file_atomic(i->path, new_path, read_only ? 0444 : 0644, false, FS_NOCOW_FL); + break; + + default: + return -EOPNOTSUPP; + } + + if (r < 0) + return r; + + STRV_FOREACH(j, settings) { + r = clone_settings_file(*j, new_name); + if (r < 0 && r != -ENOENT) + log_debug_errno(r, "Failed to clone settings %s, ignoring: %m", *j); + } + + return 0; +} + +int image_read_only(Image *i, bool b) { + _cleanup_release_lock_file_ LockFile global_lock = LOCK_FILE_INIT, local_lock = LOCK_FILE_INIT; + int r; + assert(i); + + if (IMAGE_IS_VENDOR(i) || IMAGE_IS_HOST(i)) + return -EROFS; + + /* Make sure we don't interfere with a running nspawn */ + r = image_path_lock(i->path, LOCK_EX|LOCK_NB, &global_lock, &local_lock); + if (r < 0) + return r; + + switch (i->type) { + + case IMAGE_SUBVOLUME: + + /* Note that we set the flag only on the top-level + * subvolume of the image. */ + + r = btrfs_subvol_set_read_only(i->path, b); + if (r < 0) + return r; + + break; + + case IMAGE_DIRECTORY: + /* For simple directory trees we cannot use the access + mode of the top-level directory, since it has an + effect on the container itself. However, we can + use the "immutable" flag, to at least make the + top-level directory read-only. It's not as good as + a read-only subvolume, but at least something, and + we can read the value back.*/ + + r = chattr_path(i->path, b ? FS_IMMUTABLE_FL : 0, FS_IMMUTABLE_FL); + if (r < 0) + return r; + + break; + + case IMAGE_RAW: { + struct stat st; + + if (stat(i->path, &st) < 0) + return -errno; + + if (chmod(i->path, (st.st_mode & 0444) | (b ? 0000 : 0200)) < 0) + return -errno; + + /* If the images is now read-only, it's a good time to + * defrag it, given that no write patterns will + * fragment it again. */ + if (b) + (void) btrfs_defrag(i->path); + break; + } + + default: + return -EOPNOTSUPP; + } + + return 0; +} + +int image_path_lock(const char *path, int operation, LockFile *global, LockFile *local) { + _cleanup_free_ char *p = NULL; + LockFile t = LOCK_FILE_INIT; + struct stat st; + int r; + + assert(path); + assert(global); + assert(local); + + /* Locks an image path. This actually creates two locks: one + * "local" one, next to the image path itself, which might be + * shared via NFS. And another "global" one, in /run, that + * uses the device/inode number. This has the benefit that we + * can even lock a tree that is a mount point, correctly. */ + + if (path_equal(path, "/")) + return -EBUSY; + + if (!path_is_absolute(path)) + return -EINVAL; + + if (stat(path, &st) >= 0) { + if (asprintf(&p, "/run/systemd/nspawn/locks/inode-%lu:%lu", (unsigned long) st.st_dev, (unsigned long) st.st_ino) < 0) + return -ENOMEM; + } + + r = make_lock_file_for(path, operation, &t); + if (r < 0) + return r; + + if (p) { + mkdir_p("/run/systemd/nspawn/locks", 0700); + + r = make_lock_file(p, operation, global); + if (r < 0) { + release_lock_file(&t); + return r; + } + } + + *local = t; + return 0; +} + +int image_set_limit(Image *i, uint64_t referenced_max) { + assert(i); + + if (IMAGE_IS_VENDOR(i) || IMAGE_IS_HOST(i)) + return -EROFS; + + if (i->type != IMAGE_SUBVOLUME) + return -EOPNOTSUPP; + + /* We set the quota both for the subvolume as well as for the + * subtree. The latter is mostly for historical reasons, since + * we didn't use to have a concept of subtree quota, and hence + * only modified the subvolume quota. */ + + (void) btrfs_qgroup_set_limit(i->path, 0, referenced_max); + (void) btrfs_subvol_auto_qgroup(i->path, 0, true); + return btrfs_subvol_set_subtree_quota_limit(i->path, 0, referenced_max); +} + +int image_name_lock(const char *name, int operation, LockFile *ret) { + const char *p; + + assert(name); + assert(ret); + + /* Locks an image name, regardless of the precise path used. */ + + if (!image_name_is_valid(name)) + return -EINVAL; + + if (streq(name, ".host")) + return -EBUSY; + + mkdir_p("/run/systemd/nspawn/locks", 0700); + p = strjoina("/run/systemd/nspawn/locks/name-", name); + + return make_lock_file(p, operation, ret); +} + +bool image_name_is_valid(const char *s) { + if (!filename_is_valid(s)) + return false; + + if (string_has_cc(s, NULL)) + return false; + + if (!utf8_is_valid(s)) + return false; + + /* Temporary files for atomically creating new files */ + if (startswith(s, ".#")) + return false; + + return true; +} + +static const char* const image_type_table[_IMAGE_TYPE_MAX] = { + [IMAGE_DIRECTORY] = "directory", + [IMAGE_SUBVOLUME] = "subvolume", + [IMAGE_RAW] = "raw", +}; + +DEFINE_STRING_TABLE_LOOKUP(image_type, ImageType); |